1. Field of the Invention
The present invention relates to a compressor, constituting a refrigeration cycle circuit in a refrigerating apparatus, which is a rotary compressor having a plurality of cylinder chambers partitioned by an intermediate partition plate.
2. Description of the Related Art
In a refrigerating apparatus, a multi-cylinder type rotary compressor is used as a compressor constituting the refrigeration cycle circuit.
The multi-cylinder type rotary compressor has a plurality of cylinders partitioned by an intermediate partition plate in the axial direction of the rotating shaft.
A roller is fitted on an eccentric portion mounted on the rotating shaft. When the rotating shaft is rotated, the roller is driven, eccentrically rotating along the inner circumferential surface of the cylinder chamber.
A vane biased by a spring contacts the outer circumferential surface of the roller and divides the cylinder chamber into high- and low-pressure chambers.
The refrigerant gas is drawn by vacuum into the low-pressure chamber. As the roller is eccentrically pivoted, the refrigerant gas is compressed as it is transferred to the high-pressure chamber, and is discharged when its pressure is increased to a predetermined high pressure.
In such a multi-cylinder type compressor, the plurality of independent cylinder chambers perform compression. Therefore, when compared with a conventional rotary compressor having only one cylinder chamber, the refrigerating capability is improved.
However, the refrigerating capability is always constant and cannot be changed in accordance with a load.
Published Unexamined Japanese Patent Application Nos. 62-225794 and 62-70686 and Published Examined Japanese Patent Application No. 2-25037 disclose inventions that can eliminate inconvenience of this type.
According to Published Unexamined Japanese Patent Application No. 62-225794, release paths for returning part of the gas being compressed to the suction side are connected to two cylinders.
Capacity control valves are provided to these release paths in order to control the compression capacities of the respective cylinders.
The release paths are merged after passing through the capacity control valves.
According to Published Unexamined Japanese Patent Application No. 62-70686, a plurality of cylinder chambers are partitioned by an intermediate partition plate.
These cylinder chambers communicate with each other through a path. This path is opened/closed by a valve unit.
The path is formed in the intermediate partition plate. The valve unit is operated by a back pressure or is driven by a solenoid valve.
According to Published Examined Japanese Patent Application No. 2-25037, a high-pressure chamber of one of adjacent cylinders and a low-pressure chamber of the other of the adjacent cylinders communicate with each other through a path formed in an intermediate partition plate.
An opening/closing mechanism is provided for closing and opening the path in the normal operation and in the decreased capability operation, respectively.
In any of the disclosed techniques, an opening/closing mechanism such as a valve is operated to open or close the path, so that the refrigerating capability can be variably controlled in accordance with a load.
The release paths of Published Unexamined Japanese Patent Application No. 62-225794 are formed to extend from the outer circumferential surfaces of the respective cylinders to the inner circumferential surface of the intermediate partition plate along the thicknesses of the cylinders and the intermediate partition plate.
The capacity control valves are provided midway along the release paths provided to the respective cylinders.
Therefore, both the cylinders and the intermediate partition plate must be subjected to necessary working, resulting in cumbersome working.
Since the release paths must accurately communicate with each other from the cylinders to the intermediate partition plate, high-precision working and assembly are required.
The number of the capacity control valves must corresponds to that of the cylinders, resulting in a large number of components. As the capacity control valves are located midway in the release paths, the assembly becomes cumbersome.
According to Published Unexamined Japanese Patent Application No. 62-70686 and Published Examined Japanese Patent Application No. 2-25037, all of the path and the valve unit or opening/closing mechanism for opening/closing the path are provided within the thickness of the intermediate partitioning plate.
A intermediate partition plate is usually formed to have a minimum thickness needed for partitioning in order to promote weight reduction of the compressor.
A long lateral hole having a diameter smaller than the thickness of the thin intermediate partition plate must be formed by working to extend from the outer circumferential surface of the thin intermediate partition plate to its inner circumferential surface.
Even slight off-centering will cause the distal end of the hole to project from the side surface of the intermediate partition plate during working.
Even after accurate hole formation is performed, an operation for inserting a slider and a spring in the thin hole and assembling them is needed, resulting in a cumbersome operation.
The size of a necessary portion becomes very small, the variable-capability capacity becomes small, and a sufficient effect cannot be obtained.